The present invention relates to a BGA (Ball Grid Array) socket, and especially to a BGA socket for reliably engaging with a CPU.
A BGA socket having a compact dimension is commonly used within a notebook computer. The BGA socket such as the one disclosed in U.S. Pat. No. 5,730,615 usually includes a base and a cover slidable above the base thereby actuating pins of a CPU inserted into the socket to engage with terminals of the base.
Referring to FIG. 1, a conventional BGA socket 1 includes a cover 11 and a base 10 arranged under the cover 11. The cover 11 is slidably coupled to the base 10. The cover 11 defines a plurality of apertures (not shown) in alignment with passageways (not shown) of the base 10 for receiving corresponding terminals (not shown) therein. A plurality of solder balls (not shown) is disposed proximate the terminals between the base 10 and a mother board (not shown). Processed by an infrared reflow soldering method, the solder balls become molten thereby connecting the terminals to the mother board. A recess 12 is defined in the base 10 proximate a lateral edge thereof. A hole 13 is defined through the cover 11 corresponding to the recess 12 of the base 10. A rod 120 is disposed to extend through the hole 13 and an end 14 of the rod 120 is received in the recess 12. Pins (not shown) of a CPU 2 are inserted through the aperture into the passageways. Initially, no spring engagement exists between the pins and the terminals. Thereafter, the rod 120 is pivoted in a counterclockwise direction with the end 14 as a pivot. The cover 11 is laterally pushed thereby actuating the pins of the CPU 2 to engage with the terminals of the BGA socket 1.
However, besides the concretionary solder sites, no other retention means exists between the base 10 and the mother board. The action of the rod 120 exerts stress in the base 11 thereby possibly deforming the base 11. In addition, such a stress acts on the solder sites thereby adversely affecting quality of electrical connection between the BGA socket 1 and the mother board.